The 13C-NMR-DEPT data of compound 1 showed that the chemical shift of C-6 of the glucose linked with genin and that of C-4 of the second glucose were both 7 ppm downfield; this sug- gested that the linkage position between the two glu- coses was 6f1, and that between the second glucose and the rhamnose was 4f1. The long-range 13C-1H COSY spectrum further confirmed that the rhamnose linked with the second glucose at C-4 position, showing a cross peak between the proton at δ 4.85 (rham - 1) and the carbon at 78.6 (glc - 4) (Table 1). The coupling- constant data of the anomeric protons in 1H NMR indicated the configuration of the glucoses was â-ori- ented (d, J ) 7 Hz), and that of rhamnose was R-oriented (br s).15 Therefore, the structure of the sugar moieties of 1 was established as R-L-rhamopyranosyl- (1f4)-O-â-D-glucopyranosyl(1f6)-O-â-D-glucopyrano- side. Moreover, this sugar residue was of the same type as those found in other triterpene glycosides isolated from Schefflera
The 13C-NMR-DEPT data of compound 1 showed that the chemical shift of C-6 of the glucose linked with genin and that of C-4 of the second glucose were both 7 ppm downfield; this sug- gested that the linkage position between the two glu- coses was 6f1, and that between the second glucose and the rhamnose was 4f1. The long-range 13C-1H COSY spectrum further confirmed that the rhamnose linked with the second glucose at C-4 position, showing a cross peak between the proton at δ 4.85 (rham - 1) and the carbon at 78.6 (glc - 4) (Table 1). The coupling- constant data of the anomeric protons in 1H NMR indicated the configuration of the glucoses was â-ori- ented (d, J ) 7 Hz), and that of rhamnose was R-oriented (br s).15 Therefore, the structure of the sugar moieties of 1 was established as R-L-rhamopyranosyl- (1f4)-O-â-D-glucopyranosyl(1f6)-O-â-D-glucopyrano- side. Moreover, this sugar residue was of the same type as those found in other triterpene glycosides isolated from Schefflera
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